I got a new cell phone but I am making monthly installments so should I include the full amount or what I paid monthly for that year? Also for the service too monthly?

Where are you entering this? Do you have a business?

When you use a cell phone for both personal and business, the amount you deduct depends on how much you are using your phone for both personal and business use. This applies to the cost of the phone and the monthly service.

Are you using it 50% business and 50% personal, or maybe 75% business and 25% personal? Whatever it is, you need to come up with a reasonable percentage for each use and then you can take the percentage of the expense that is related to business use. 

You can only deduct payments actually made, so you would not include the full amount, only what you paid.